Adhesive tape



Patented Jan. 14,1936

UNITED STATES PATENT oFFics ADHESIVE TAPE Ernest L. Kallander and Gardner n. Alden, Framingham, Mass, assignors to Dennison Manufacturing Company, Framingham, Mass.,

a corporation of Massachusetts No Drawing. Application January 10, 1934,

' Serial No. 706,074

13 Claims.-

This invention relates to adhesive tapes and constitutes a continuation in part of our application Serial No. 642,762, filed November 15,1932.

In our parent application; we have pointed out that a solution of .so-called vinylite gums or vinyl resins" is highly effective as an adhesive even in connection with cellophane" of the waterproof variety. These gums, which are procurable on the open market, are condensation products consisting essentially of the condensed esters of vinyl alcohol, e. g., vinyl chloride, vinyl acetate, or mixtures of such esters. They are characterized by their water-insolubility, odorlessness, transparency, stability, and flexibility when'in thin films. They are soluble in various organic solvents, being highly soluble in various ester solvents, such as ethyl acetate and butyl' acetate, and in various ethers and ketones. They are also soluble in carbon tetrachloride and in the various aromatic hydrocarbons, such as benzol, but they are soluble only to a limited extent in the aliphatic hydrocarbons, such as naphtha or gasoline, which have the efiect'of swelling them or causing only incipient solution. We have found that such compounds as tetrahydronaphthalene (tetralin), decahydronaphthalene (decalin), a mixture of cyclohexanol and cyclohexanone (hexalin), and various polymerized chlorinated diphenyls also have the effect of plasticizing and renderingmore adhesive the vinyl resins. At this point, it might be mentioned; that the Y foregoing compounds, especially aliphatic hydro- (1) Vinnapas B (2) Mowilith N (3) {*Vinylite A The first two are comparatively soft and plastic; the third is harder. All of the foregoing. vinyl resins,'however, are polyvinyl acetatesand yield solutions which, as the solvent is evaporated therefrom, become highly viscous or stringy and are hence highly satisfactory for the purposes of our invention. By choosing the appropriate solvent vehicle, namely, one which evaporates quickly, and by providing a sufficient amount of gum in the solution, it is possible to realize almost'immediate stickness or tackiness in a thin coating-or'fllm of the solution exposed to the air. Thus, one may use benzol, carbon tetrachloride, ethyl acetate, or similar volatile solvent in preparing the vinyl resin solution.

Such a solution is'of value in sticking together the edges of waterproof -cellophane wrappers 6 such as are employed for cigarette packages,

-cigars, or the like. When the solution is applied as a coating to paper or cloth which is to serve for making the adhesive tapes of the present invention and is permitted to set or dry 10 thereon, we have observed that there is sufficient plasticity in the coating to give rise to a tendency for "blo'cking or adhesion of the successive layers constituting a package. It might here be mentioned that the vinyl resins tend to cohere l5 and that adjacent films of such resins tend naturally to adhere to one anotherv even in a dry state. We have discovered, however, that it is possible to destroy such tendency to adhere by compounding with the vinyl resin solution an ap- 20 propriate amount of cellulose ester, such as nitrocellu'lose or cellulose acetate, or cellulose ethers, such as ethyl or methyl cellulose, or similar cellulose derivatives, which function to increase the hardness or rigidity of the dried coating. When 25,

nitrocellulose, cellulose acetate, .or other cellulose derivatives are added to the solution, the solvent vehicle should be one which acts as a solvent for both the vinyl resin and the cellulose ester.

- Assuming, for example, that nitrocellulose is the 30 cellulose ester, we may use ethyl acetate, acetone,

8. mixture of ethyl alcohol and ether, or equivalent solvents or solvent mixtures.

Adhesive tapes coated in accordance with our invention must be moistened with a suitable liquid 35 which quickly imparts stickiness or tackiness .to

' the dried coating. Assuming that the dried coating consists essentially only of vinyl resin, we have discovered that the moistening liquid should contain not only a true solvent of the vinyl resin, 40 but preferably also a swelling agent therefor, since otherwise it is impossible to impart adequate tackiness to the coating quickly or to realize a permanently tenacious bond with cellophane.

As already indicated, there are various liquids,'45

such as naphtha or gasoline, which swellthe vinyl resin. These swelling liquids may be mixed with benzol, carbon tetrachloride, or other true solvents of the vinyl resin, toproduce'the desired moistening liquid. When the coating contains both a vinyl resin and-a cellulose ester, such as nitrocellulose ofcellulose acetate, or cellulose others, such as ethyl or methyl cellulose, or similar cellulose derivatives, the moisteninglliquid for the coating preferably includes a true solventof the vinyl resin, a swelling agent therefor, and" i a. suitable solvent of the cellulose derivative. In

' compounding nitrocellulose, for instance, with the vinyl resin, we prefer to use only up to about 30 parts of nitrocellulose to 70 parts of vinyl resin.

The solvent of the vinyl resin and the cellulose ester may be one and the same, or be a mixture of a solvent specific for the vinyl resin and a solvent specific for the cellulose ester. When the moistening liquid contains a suitable swelling the cellulose ester may be used in lieu of, or together with, the swelling agent for the vinyl resin. Thus, we may add to the moistening liquid nonvolatile plasticizing agents, such as dibutyl phthalate and tricresyl phosphate, which function to plasticize both the vinyl resin and the cellulose ester in the coating. Inasmuch as these plasticizers have the effect of decreasing the tackiness attainable in the coating, they are preferably not employed excepting in those instances when it is undesirable to employ gasoline or like swelling agents, on account, of their objectionable odor; or they are employed in amounts so small that their effect on the tackiness attainable in the coating will be negligible.

We wish again to stress the fact that the mois tening liquid should preferably contain not only a true solvent of the vinyl resin, but also a volatile aliphatic hydrocarbon or volatile hydrocarbons of the nature of tetrahydronaphthalene and decahydronaphthalene. It might be well for us here to give a picture of the mechanism probably entering into the action of such a moistening liquid. Thus, in moistening a dry film with, let us say, a moistening liquid consisting of one part of alcohol and two parts of naphtha, the alcohol is probably very quickly absorbed by the film, making the resin plastic. The alcohol evidently carries with it a certain amount of naphtha which is also absorbed by the resin. However, since the naphtha is not a true solvent of the resin and since the alcohol and naphtha are miscible in all proportions, the naphtha evidently restrains the solvent action of the alcohol and accordingly represses the solution of the resin. We give this picture for the reason that we know that when resins become liquid or unduly swollen, their tackiness is diminished on account of their reduced viscosity. Apparently, what we do is to effect a controlled salvation, that is, to create a condition such that we form a firm and coherent gel, yet one which hasthe desired adhesiveness and plasticity.

We shall now deal with specific examples of applying our invention in practice. Assuming that paper is to be the base of the adhesive tapes of the present invention, the paper is preferably precoated to provide a ground which prevents the adhesive composition from penetrating into, or being unduly absorbed by, the paper. To this end, the paper may be precoated with fillers, such as precipitated calcium sulphate and/or precipitated calcium carbonates, which are preferably applied together with a suitable size or binder, such as water-soluble casein, as an aqueous paste. To the dried coating on the paper,

we apply the adhesive composition of the present invention. A preferred composition is one made up by dissolving '40 parts by weight of vinyl'resin gum in 60 parts by weight of suitable solvent, e. g., 30 parts of ethyl acetate and 30 parts of benaol. It is, as already indicated'preferable that such compositions contain an appropriate amount of cellulose ester, wherefore, we preferably add to the foregoing composition about 4 to 12 parts by weight of cellulose nitrate, or equivalent cellulose ester. The resulting composition is quite thin and fluent, and so lends itself to easy and smooth application by the usual coating or spreading machines, as a thin film on the paper The paper is then dried and cut into ribbons or hands of the desired'width and accumulated as rolls of adhesive tape.

Thereare various moistening liquids which may be used to develop tackiness in the set coating to enable it to be stuck to a surface. The selection of the solvents will depend primarily upon conditions, that is, upon whether solvents having strong odors, are permissible, upon the speed of drying, and the degree of tackiness or speed of adhesion required and upon the nature of the surface to be stuck to. We might illustrate by citing the following moistening liquids:-

For straight vinyl resin coatings l. 50 lbs. toluol 30 lbs. high grade naphtha E 50 lbs. benzol 30 lbs. high grade naphtha Tetrahydronaphthalene (tetralin) Decahydrcnaphthalene (decalln) A mixture of cyclohexanol and cyclohexanone (hexalin) y l 50 lbs. carbon tetrachloride 1o lbs-high grade nap tha 8 lbs. liquid polymer zed chlorinated diphenyl 2 lbs. dibutyl phthalate 50 lbs. high grade naphtha 40 lbs. benzol' For mixtures of vinyl resin and nitrocellulose 8. lbs. denatured alcohol 20 lbs. tetralin 1 9. 40 lbs. methanol 25 lbs. high grade naphtha 80 lbs. high grade naphtha 40 lbs. ethyl a1coholdenatured 10 lbs. liquid chlorinated diphenyl 40 lbs. ethyl acetate 2 lbs. methyl acetate 1 lb. high grade naphtha 80 lbs. 60 B. naphtha 100 lbs. denatured ethyl alcohol 20 lbs. methyl acetate 8 lbs. liquid polymerized chlorinated diphenyl 2 lbs. dibutyl phthalate lbs. monomethyl ether of ethyleneglycol or 90 lbs. denatured alcohol 80 lbs. monomethyl ether of ethylene glycol 40 lbs. denatured alcohol 7 6 lbs. liquid chlorinated polymerized diphenyl 7 mixtures of vinyl and cellulose acetate 50 lbs. acetone 30 lbs. high grade naphtha 50 lbs. ethyl lactate H 30 lbs. high grade naphtha 50 lbs. monomethyl ether of ethylene glycol 30 lbs. high grade naphtha 50 lbs. diglycol ether 30 lbs. high grade naphtha We might'gcomment on the above-noted moistening liquid-.fbrmulzz-t #1 formula can be used where a high degree of adhesion is desirable and the odor of toluol and naphtha is permissible. It is comparatively For cheat #2 is similar but is quick evaporating.

#3 has exceptionally quick tack but due to its very strong odor would seem to have but limited application. This moistening liquid promotes the highest degree of adhesion to various surfaces.

#4 and #5 are similar to #3, though of less odor and less tack-producing properties.

#6 is exceptionally quick drying and is unsuitable for hand-moistening.

#7 gives exceptional adhesion; has high volatility, but develops a relatively poor degree of tackiness.

#8 is of medium volatility, gives a high degree of adhesion and fair tackiness, but has a rather bad odor.

#9 is of high volatility, gives good adhesion, and does not have objectionable odor for most purposes.

#10 is of medium volatility, is more suitable for hand work, and promotes good adhesion to most surfaces, particularly when used liberally.

#11 is highly volatile, gives good adhesion, but due to the use of straight lacquer solvent therein, it has the objectionable feature of softening excessively the waterproof or lacquer type of coating on regenerated cellulose hereinbefore described, and permitting it to peel easily when subjected to slight tension.

suffers from the same objection that #11 does with respect to the softening of the lacquer type of surface to which our resin coatings are designed to adhere.

#15 is also desirable from the standpoint of odor, but has a higher degree of volatility than #14. It does not soften a nitrocellulose or lacquer surface, such as occurs on the moistureproof cellophane hereinbefore described.

#16 is highly volatile.

#17 is of low volatility with good solventpower.

#18 has relatively less solvent power than #17, yet is very desirable so far as concerns odor.

#19 is of medium volatility and is characterized by a strong odor. a

In producing a tape to be stuck to "cellophane closures for milk bottles, it is desirable to apply the adhesive compositions hereinbefore described to one face of the paper tape, and to apply cellulose acetate, cellulose nitrate, or other ester to the other face of the tape. The tape is moistened with the appropriate moistening liquid and stuck to the skirt portion of the cellophane closure with one of its end portions overlapping and stuck to the cellulose ester coating on the other end portion. The primary object in using cellulose acetate or'cellulose nitrate as a coating on one face of the tapeis to render the moistened vinyl resin coating on the opposite face more quickly and strongly adherent to the first-mentioned coating when a lap is made. The paper tape is preferably precoated with suitable fillers, as hereinbefore described, on both its faces. It is more economical to use cellulose acetate or cellulose nitrate on one face of the tape and the vinyl resin coating composition on the face to be secured to the cellophane. The moistening liquid develops the desired tackiness in the vinyl resin coating composition and ensures excellent bonding with the cellulose ester coating, as well as with the cellophane, as both coatings are capable of adhesive activation by the various moistening liquids hereinbefore disclosed for such purpose. While it is preferable to use cellulose nitrate, cellulose acetate, or similar cellulose esters in the vinyl resin composition for coating the face of the tape to be secured to the cellophane" and to use solutions of essentially only such esters as the composition for coating the opposite face of the tape, nevertheless, it is possible to use cellulose ethers, like ethyl and methyl cellulose, and other cellulose derivatives in lieu of'the cellulose esters.

These other cellulose derivatives should. of course, be capable of adhesive activation by the same organic liquids as activate the vinyl resins, as is true of ethyl and methyl cellulose, which are in fact soluble in solvents of the vinyl resins. So, too, it is possible to use in lieu of solutions of cellulose derivatives other adhesive coating compositions, such as solutions of copal, ester gum, and other natural and synthetic resins which are capable of adhesive activation by the a same organic liquid that activates the vinyl resins, particularly for coating the face of the tape that is merely to be lapped over, that is, that is not to be stuck to cellophane.

In the case of the various gummed articles hereinbefore mentioned, it is desirable that both faces of the paper or cloth be precoated with suitable sizes, as this tends to inhibit blocking of the successive layers constituting a package. The coating of the paper with casein, glue, or' starch compositions, makes possible this desideratum. So, too, papers which have been body-sized with glue or starch answer our purposes. The use of fillers, as hereinbefore described, in the coating compositions makes possible the attainment of a smooth surface and attractive coloring, as the coating composition may of course containplgments or other coloring agents. When the vinyl resin adhesive composition is applied to one face and cellulose acetate or other cellulose ester is applied to the other face of the paper, as in the tape hereinbefore described, there is no tendency for blocking" of the paper when it is wound into rolls. I

In those instances when it may be desirable to compound the vinyl resin with other resins and more particularly with natural resins of the character of rosin and copal, it is preferable to use a subordinate amount of these natural resins, say up to about of the weight of the vinyl resin, as in such case, the natural resin does not unduly detract from the desired properties, especially the quickness of tack and the tenacity of adhesion,

inherent in the vinyl resin,

We shall now give a definition of what we mean by the following expressions: solvents, smelling agents, and plasticizers, as used in the foregoing description; For thepurposes of our invention, a solvent mightbe defined as a liquid which is capable of dissolving the vinyl resin to manentiy, conducing to permanent bond or ad- 7 .rial capable of adhesive activation by an organic liquid, both said coatings existing as distinct layers on said base and being capable of adhesive activation by a common organic liquid and capable of adhering firmly to each other when thus activated but said coatings being substantially without tackiness prior to such activation.

2. An adhesive tape consisting of a flexible fibrous base coated on one face with vinyl ester resin and on the other face with cellulose derivative, both the'vinyl ester resin and the cellulose mrivative coatings existing as distinct layers on said base and being capable of adhesive activation by a common organic liquid and capable of adhering firmly to each other when thus activated but said coatings being substantially without tackines's prior to such activation.

3. An adhesive tape consisting of a fiexible fibrous base carrying a primary coating of size andflller on both its faces and carrying on one face a secondary surface coating of vinyl ester resin and on the other face a secondary surface coating of cellulose derivative, both the vinyl ester resin and the cellulose derivative coatings existing as distinct layers on said base and being capable of adhesive activation by a common organic liquid and capable of adhering firmly to each other when thus activiated but said coatings being substantially without tackiness prior to such activation.

4. A paper tape, one face of which is coated with a mixture of vinyl ester resin and a cellulose ester, and the other face of which is coated with a cellulose ester, the coatings on both faces existing as distinct layers on said base and being capable of adhesive activation by a common organic liquid and capable of adhering firmly to each other when thus activated but said coatings being substantially without tackiness prior to such activation.

5. A paper tape, one face of which is coated with a mixture of vinyl ester resin and a cellulose ester wherein the resin preponderates in amount, and the other face of which is coated with a cellulose ester, the coatings on both faces existing as distinct layers on said base and bein capable of adhesive activation by a common organic liquid and capable of adhering firmly to each other when thus activated but said coatings being substantially without tackiness prior to such activation.

6. A paper tape, one face of which is coated with a mixture of vinyl ester resin and cellulose acetate, and the other face of which is coated with cellulose acetate, the coatings on both faces existing as distinct layers on said base and being capable of adhesive activation by a common organic liquid and capableof adhering firmly to each other when thus activated but said coatings being substantially without tackiness prior to such activation.

7. A paper tape, one face of which is coated with a mixture of vinyl ester resin and cellulose acetate wherein the resin preponderates in amount and the other face of which is coated with cellulose firmly to each other when thus activated.

acetate, the coatings on both faces existing as distinct layers on said base and being capable of adhesive activation by a common organic liquid and capable of adhering firmly to each other when thus activated but said coatin s being sub- 5 stantially without tackiness prior to such activation.

8. A paper tape, one face of which is coated with a mixture of vinyl ester resin and'nitrocellulose and the other face of which is coated with nitrocellulose, the coatings on both faces existing as distinct layers on said base and being capable of adhesive activation by a common organic liquid and capable of adhering firmly to each other when thus activated but said coatings being substantially without tackiness prior ,to such activation.

9. A paper tape. one face of which is coated with a mixture of vinyl ester resin and nitrocellulose wherein the resin preponderates in amount 20 and the other face of which is coated with nitrocellulose, the coatings on both faces existing as "distinct layers on said base and being capable of adhesive activation by a common organic liquid and capable of adh'efring firmly to each other 25 when thus activated but said coatings being substantially without tackiness prior to such activa tion.

10. A paper tape whose surface pores are filled to render it lowly absorbent and which is coated on one face with vinyl ester resin and on the other face with another substance capable of adhesive activation by an organic liquid,.both said coatings existing as distinct, substantially dry layers on said paper base and being capable of 3: adhesive activation bya common organic liquid and capable of adhering firmly to each other when thus activated.

11. A paper tape'whose surface pores are filled with solids, including inorganic solids, to render it lowly absorbent and which is'coated on one face with vinyl ester resin and on the other face with another substance capable of adhesive activation by an organic liquid, both said coatings existing as distinct, substantially dry layers on 4 said paper base and being capable of adhesive activation by a common organic liquid and capable of ;adhering firmly to each other when thus activated.

12. A paper tape whose surface pores are filled s to render it lowly absorbent and which is coated on one face with vinyl ester resin and on the other face with cellulose derivative, both the vinyl ester resin and the cellulose derivative coatings existing as distinct, substantially dry layers on said a paper base and being capable'of adhesive act vation by a common organic liquid and capable of adhering firmly to each other when thus activated.

13. A paper tape whose surface pores are filled with solids, including inorganic solids, to render it lowly absorbent and which is coated on one face with vinyl ester resin and on the other face with cellulose derivative, both the vinyl ester resin and the cellulose derivative coatings existing 1 as distinct, substantially dry layers on said paper base and being capable of adhesive activation by a common organic liquid and capable of adhering ERNEST L. KALLANDERQ oammna a. ALDEN. 

